Include additional files

[motto]

upstream name should be unique per entire config, you could name it in
nginx.conf and than reference to its name from different your includes.
like:
         upstream loadbalancer  {
                server 192.168.0.1:8080; 
                server 192.168.0.2:8080; 
                server 192.168.0.3:8080; 
                server 192.168.0.4:8080; 
        }

than in certain location (in included file for example)
            proxy_pass         http://loadbalancer;

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,238628,238629#msg-238629